Airplane control surface



. June 6, 1950 Filed July 22, 1944 F. M. DE LAVAL 2,510,561

AIRPLANE CONTROL SURFACE 4 Sheets-Sheet l I N V EN TOR. FULVJ /ZDE LAVIAL 2 AGENT June 6, 1950 F, M, 95 LAVAL 2,510,561

AIRPLANE CONTROL SURFACE Filed July 22, 1944 4 Sheets-Sheet z IN V EN TOR. Fz/Lvm MDELAVAL June 6, 1950 F, 5 L A 2,510,561

AIRPLANE CQNTROL SURFACE 4 Sheets-Sheet 3 Filed July 22, 1944 IN V EN TOR. FULW ZZ'DELAVAL AGENT June 6, 1950 F. M. DE LA vAL 2,510,561

AIRPLANE CONTROL SURFACE Filed July 22, 1944 4 Sheets-Sheet 4 IN VEN TOR. FULWU M 175 LAVAL 2 AGENT Patented June 6 1950 AIRPLANE CONTROL SURFACE Fulvio M. de Laval, Los Angeles, Calif., assignor to Lockheed Aircraft Corporation, Burbank,

Calif.

Application July 22, 1944, Serial No. 546,131

Claims.

This invention relates to aircraft and it is a general object of the invention to provide an efficient, practical and dependable airplane of unique design and operation. Although the principles of the invention are not restricted to any given class of aircraft 1 will herein refer to heavierthan-air craft it being understood that the invention is capable of embodiment in air-borne vehicles of various classes. l

Another object of the invention is to provide an airplane characterized by a single tail surface element which serves as both the longitudinal and directional stabilizing and control surface means. In the airplane of this invention a single tail element replaces the vertical fin, horizontal stabilizer, rudders and elevators of the conventional empennage-or tail assembly, thus greatly simplifying the design and fabrication.

Another object of the invention is to provide an aircraft of the character referredto in which the single tail element is differentially controllable to obtain directional control and pitch or elevational-control. This provides for material simplification and consolidation of the essential controls with an accompanying reduction in 3 weight and the .cost of manufacture and maintenance.

Another object of the invention is to provide an airplane characterized by an especially advantageous relationship between, the propellers or other propulsive means, and the single empennage or tail element mentioned above. The tail element may be in the form of a continuous ring or annular unit arranged in surrounding relation to the propellers. This. removes the tail surfaces ,from-theslip streamof the propeller eliminating the early formation of a shock wave on the tail surfaces, and'eliminating buffeting of the tail surfaces due to fnibbling and like phenomena. In

conventional airplane design the tail surfaces are often in the slip stream of the propellers and are therefore subject to the accompanying shock wave eflect,b'uffeting, etc. This is completely avoided in the airplane of the present invention. Furthermore, the surrounding relationship of the of construction and maintenance and is of particular importance in the case of aircraft intended for transport and use on water borne craft such as aircraft carriers, where it is desirable to keep the length of'the airplane to a minimum.

A further object of the invention is to provide an airplane of the character mentioned in which the tail surfaces are symmetrically disposed about or concentric with the longitudinal axis of the craft.

A still further object of the invention is to provide an airplane of the character above referred to embodying a simple practical and dependable control for the tail ring operable from a single station and if desired by manipulation of a single wheel, or the like, for changing the angular position of the tail ring for either directional control or elevational control of the airplane or both. The control of the invention is operable to tilt the tail ring about atransverse or generally horizontal axis to provide for elevational control of the craft, and is operable to 'yaw the tail ring to provide for steering control of the airplane. The two dimensions of control may be concurrently obtained by the differential control feature ofthe invention. Furthermore, the ailerons or other conventional control surface elements of the airplane may likewise be operated by the single control means of the invention.

Other objects and advantages of the invention .will become apparent from the following detailed description of typical preferred embodiments wherein reference will be made to the accompanying drawings in which:

. Figure l is a plan view of an airplane embodying the present invention;

Figure 2 is a front elevation of the airplane; Figure 3 is an enlarged diagrammatic perspective outline view of the airplane illustrating the control system for the tail ring, andshowing other internalpartsof the airplane;

Figure4 is an enlarged diagrammatic perspective view of apportion of the control system;

Figure 5 is an enlarged fragmentary vertical section of a portion of the tail ring and the mech- .anism for operating the same to obtain elevational control; V

Figure 6 is a fragmentary diagrammatic perspective view of another embodiment of the invention illustratingthe tail ring and the mechanisms for operating the same;

Figure 7 is an enlarged fragmentary perspective view of the connections between the tail ring and operating rods of the control system. i

In thedrawings the invention is illustrated em wings If.

bodied in a pusher-type monoplane having fuselage l and sustentation means in the form of wings II. The power plant or engine i2 is shown arranged in the nose or forward portion of the fuselage In with a suitable drive [3 extending rearwardly therefrom to a pair of dual rotation propellers I4 located at the tail or aft end of the fuselage. The wings- H are equipped with the usual ailerons l5 operated or controlled by cables 56 engaged over appropriately positioned guide pulleys ll. A suitable cooler l8 having a blower I9 operated by the drive l3 is provided in. the rear portion of the fuselage Ill and. is supplied with air by ducts 20 leading to boundary layer slots 2| in the upper surfaces of the wings ll adjacent their points of juncture with the fuselage Ill. The air leaving the cooler ta discharges rearwardly around the spinners 22 of the. propellers M. In some instances it may be desired. to reverse the relationship between the cooler I8 and blower [9 so that the air leaving the blower, discharges from the boundary layer slots. It should be observed that the fuselage f0 may be quite short with the pusher propellers arranged but a short distance rearwardly of the Further it should be noted that the conventional tail assembly or empennage is absentif'rom the aft end of. the fuselage.

The invention provides a novel and highly efiicient tail member replacing the customary empennage assembly. In the embodiment of the invention illustrated this tail member 23 is in the form of a continuous ring that is substantially cylindrical in end elevation as viewed in Figure 2,. it being understood that the configuration of trailing-edge to have a symmetrical or balanced lifting or control effect when in various angular positions. The construction of the annular tail member 23 may be varied greatly. In the particular case illustrated, the ring 23 comprises a suitable skin 24 of aluminum or aluminum alloy sheet. stock, or other suitable skin material. and

an appropriate internal supporting structure 24 The tail surface or tail ring 23 surrounds. the propulsive means and. is preferably concentric with the longitudinal axis of the airplane and the propulsion means. I-have shown the tail member 23 surrounding the two propellers. M; with suitable clearance. between the. tips of. the propellers and internal surface of the ring member. The length or axial dimension of the. tail ring 23 is. preferably such. thatthe ring protrudes beyond both propellers in the fore. and aft direction when the ring is. in. its neutral position. The tail surface or ring 23' encircling the propellers l4 substantially increases the efiiciency f the'latter in accordance with the well-known propeller-.in-tube principle. It is preferred to give the tail. ring 23 sufficient. axial length to remain in surrounding relation to the two propellers when the ring. is tilted.v and .yawed to effect pitchand directional control of the airplane, so that the propulsive efiiciency of the. propellers remains substantially unchanged during such movement or control of the tail ring. It is to be understood that the proportions of the tail ring may be varied considerably to obtain the required stabilizing eifects, to present adequate control surface area, and to bear the most efiicient relation to the particular propellers or other propulsive means employed.

The tail surface element or ring 23 is supported for yawing movement, that is, angular movement or tilting about a generally vertical axis to provide for the directional control of the craft, and is also supported for tilting or angular movement about a transverse or generally horizontal axis to provide for elevational or pitch control of. the airplane. In. accordance with the broader aspects of the invention, the means for supporting the tail surface element or ring 23 may take various forms. The supporting means illustrated in the drawings are associated with or form elements of the control means for operating or movingv the tail ring. In Figures 1, 2, and 3 of the drawings there isa fin-likesupporting structure or fairing 25 extending rearwardly along the top of the fuselage Wand projecting over the upper portion of the tail ring 23. This fairing may be constructed as a part of the airframe structure and serves'tocontain and support elemerits of the control system, which is turnassist in carrying'the tail ring 23. Referring to Figure 5 it will be seen that the underside of the fairing 25 conforms toand is spaced from the upper side of the tail member or ring 23 and is provided with a longitudinally extending slot 26. A vertical bearing 21 is suitably secured to the tail ring 23 and rotatably receives a stud 28 which passes upwardly through the slot 26. A link or rod 29' within the fairing 25 is connected with the stud 28 by a pivotal connection 35 having a horizontal axis. The rod 29 extends forwardly and is connected. with a piston rod' Si by apivotal connection 32 having a generally horizontal pivotal axis. The piston rod M is supported and guided by one or more suitable bearings 33. The piston rod 3| enters a cylinder 34 mounted within the fairing 25 and is connected to a piston 35 operable in the cylinder. Itwill be seen that the tail surface or ring 23 is engaged or supported from its upper side for turning or angular movement about a generally vertical axis.

The means for supporting the tail surface or ring 23 further includes tubular arms or booms 56 projecting rearwardly from the wings H at opposite sides of the fuselage "I, see Figures 1 and 3. The booms 36 may be constructed as parts of the airframe and are suitably faired into the. wings. An operating rod or control rod 31 extends rearwardly through each boom 36, being supported at longitudinal spaced points for axial. translation by suitable bearings 38. The rods 31 extend from the rear ends of the booms 36 for connection with the tail ring 23. The rods 3T preferably occupy a horizontal plane spaced .below the longitudinal axis of the fuselage HI and tail ring 23'. In the particular airplane illustrated', the wings H are drooped adjacent the fuselage i0 and the booms 36 extend rearwardly from the drooped wing portions tube in the horizonta1 plane j'ust referred to; It tobe observed that the combination of the dorsal fairing 25 and the booms carried by the drooped wings H provide for symmetrical or' equidistant support .points for the stabilizer and control ring 23. The projecting rear ends of the rods 3'! are connected with the forward edge portion of the tail ring 23 by pivotal. connections 39 having substantially horizontal axes. The connections 39 preferably flight of the airplane as will be readily have a common horizontal axisspaced below the central longitudinal axis of the tail ring 23. It will be seen that upon operation of the piston 35 referred to. above, thetail ring 23 is rotated or tilted about the common axis of'the-connections 39. This movement of the tail surface 23 results in a change in the elevational direction of flight as will be readily apparent from an inspection of Figures 1, 2 and 3. Tubular sheaths .9 on the tail ring telescope forwardly into the booms 36 to protect the rear parts of the rods 31.

The supporting and operating rods 31 connected with the opposite side portion of the ring 23 are interconnected for simultaneous movement in opposite directions. A lever 40 is pivotally supported between its ends within the fuselage 10 at a suitable mounting 4|. The lever 40 issubstantially horizontal and it opposite ends are connected with the forward ends of the rods 31 by pivotal connections 42. It will be seen that upon operation of the lever 40 the tail ring 23 is yawed or rotated about its vertical axis. This yawing of the ring 23 controls the direction of apparent to those skilled in the art.

In accordance withthe broader aspects of the invention, the tail ring '23 may be operated or controlled by any selected or appropriate control mechanism. For example, it may be operated by mechanical means, electrical means or fluid pressure means or by a combination of such mechanisms. The invention provides a particularly advantageous hydraulic system for operating and controlling the tail ring 23 it being understood that this is only one selected form of operating mechanism. The control system illustrated includes the above referred to cylinder 34 and piston 35 and hydraulic lines 44 leading to the op- "posite ends of the cylinder 34. Upon supplying pressure to the forward end of the cylinder 34,

the tail member 23 is tilted or rotated to direct the airplane upwardly, and upon supplying fluid pressure to the rear end of the cylinder 34 the tail member is rotated about the horizontal axis 'todirect the craft downwardly. The lines 44 :of the cylinder 34 extend to a four-way valve 45 in-the fuselage I6. Fluid is supplied under pressure to the valve 45 by a line 46 extending from .a suitable hydraulic pump 41 and a "fluid return line 48 extends from the four-way valve 45 toa reservoir 49. The four-way valve 45 is preferably of the load-feel type to give the control system a desirable sensitivity and flexibility. In the drawings the four-way valve 45 is shown in a schematic manner as such valves are'well-known in the art. 1

The stem 50 of the" four-.way valve 45 is op- The upper ready manual rotation and translation. The upper end of the valve lever is connected with "the member 53 by a collar and yoke connection '54, so that the lever is operated upon axial movement of the member 53 but is unaffected by'ro- :tation of the member. A pilots wheel 55 or the equivalent is provided on the aft end of the member 53. It will be seen that pitch or elevational control of the airplane may be conveniently accomplished by simple fore and aft movement of the wheel 55. The wheel '55 is connected with the movable control member 53 by. a yoke and the pulley 66 at all times.

'easily"incorporated in the airplane. poration in the airplane provides for a high slope of balancing moment curve to allow the pivot connection 56 to provide for directional control of the airplane as will be later described.

The control system further includes an actuating cylinder 51 for operating the lever 4'0 to obtain steering or directional control. The piston rod 58 of the cylinder and piston mechanism 5'! is pivotly connected with the lever 4|) at a point spaced from its fulcrum 4|. Fluid pressure lines 60 extend from the opposite ends of the cylinder 51 to a four-Way valve 6|. The valve 6| which is illustrated in a diagrammatic fashion is preferably of the load-feel type. The four-way valve BI is secured to the manually movable control member 53 to move therewith. A fluid pressure line 62 leads from the pump 41 or the pressure line 46 to deliver pressure to the valve 6|, and a return conduit 63 extends from the valve to the return line 48. The operating stem 64 of the four-way valve 6| is operatively connected with a spoke of the wheel 55 by a suitable link 65. It will be seen that by merely tilting or rotating the wheel 55 about the pivotal axis of its mounting 56 the surface element or tail ring 23 may be yawed or rotated about a vertical axis in either direction to control the direction of flight. Further it is to be observed that full differential control of the tail surface ring 23 may be obtained by moving the wheel 55 in the longitudinal direction while at the same time rotating it about its pivotal axis 56. The arrangement is such that the instinctive or automatic operation of the wheel 55 by the pilot produces the proper or desired control of the airplane.

The controls for the ailerons |5 may be operated by the selfsame wheel 55 employed to operate the control means of the tail surface ring 23. The cable l6 of the aileron control system engages over a pulley 66 fixed to the member 53, and idler pulleys 6? direct the cable I6 so as to maintain it in active engagement with Upon rotation of the member 53 by means of the wheel 55 the cable I6 is operated to control the ailerons l5.

It is believed that the action and features of the tail surface ring 23 and its control means will be readily apparent from the foregoing de tailed description. The ring 23 may be proportioned to present sufficient surface to obtain dependable longitudinal and directional stabilization of the airplane, even where the fuselage If! lizing and control surfaces. Where the tail member 23 is in encircling relation to the propellers ,|4 it is out of the slip stream of the propellers and is therefore not subject to the undesirable Thus from an aerodynamic standpoint the tail surface in ring-like or substantially annular ,form arranged in encirclin relation to the propellers M has marked advantages over conventional aircraft tail assemblies.

The tail element 23 is a simple, readily fabricated component Its incoruse of a short tail or 'aft portion in the fuselage construction with a proportionate reduction in .73

t e W ll e t if Wate ess. es tr e deatlases scribed, the yawing and tilting of the ring-like tail member 23 may "be carried out separately or in iconsonance, by appropriate manipulation of the whee'l55 to obtain full control of the craft 'in both directions; that is, directionally and elevationally. The single tail element 23 thus "serves both as an effective stabilizing means and control surface means.

Figures 6 and 7 illustrate-an embodimentof the invention in which the annular tail surface element or ring 23 is supported and operativcly engaged at its opposite sides only, the top support or control connection being eliminated. The tail meniber 25, the lever til, the cylinder the propellers It, etc., may be the same as above described and corresponding reference numerals are applied to the corresponding parts in the several figures. In this form of the invention, the rods 3? extend rearwardly from the lever and are connected with the forward edge portions of the ring 23. The rods 3'? are connected with the ring or tail element 23 at substantially diametrically opposite points occurring in a generally horizontal plane, so that upon operation of the cylinder and piston mechanism 517 the ring is yawed or caused to rotate about a substantially vertical axis to obtain steering or directional 61 11- trol of the airplane. The cylinder and piston mechanism 5'! "for producing the directional control is governed by the four-way valve ti ab ve described.

In the construction illustrated in Figure 6,'t.i1e means for rotating or tilting the tail ring 23 about a horizontal axis to provide for control in the pitch of the airplane includes a cylinder and piston mechanism 'lil rigidly mounted on rod 31 to move therewith. Fluid pressure lines ii corresponding to the above referred to lines 46 and controllable by the four-way valve t5 communicate with the opposite ends of the cyiinder mechanisms it. The portions of the lines '3! adjacent the mechanisms iii are flexible so as to not interfere with free movement of the rods 31. A rocker lever 12 is iiulcrumed between its ends on each rod '37. Links or operating rods l3 are pivotly connected with the opposite ends of the levers l2 and extend rearwardly there from. The extremities of rods 58 are comnected with the forward edge portions or" tail ring 23 at points spaced above and below the points of connection of the rods 31 with the tail ring. The piston rods 15 of the cylinder mechanisms Ill are operatively connected with the upper ends of the levers l2. The two cylinder mechanisms 7B are connected in the fluid pressure system to be simultaneously operated in corresponding directions. Thus upon operation of the four-way valved?) in one direction, the piston rods 7-5 move rearwardly in consonance and upon operation of the four-way valve in the opposite direction the rods simul- 'taneously move forward. Upon rearward movement of'the piston rods. '15, the tail ring 23 is rotated about a horizontal axis to direct the craft upwardly, and upon forward movement of the piston rods, the tail ring is rotated to direct the airplane downwardly. It is to be observed that the cylinder mechanisms 57 and 7'8 may be sep 'arately operated to obtain independent control of the pitch and direction, or be operated simultaneously to obtain difierential control.

Any selected means may be employed .to operatively connect the rods 3'! and 13 with the generally annular tail member 23. In the drawings sleeves 18 are rotatable on vertical shafts 01' trunnions 3-9 suitably fixed to the ring. The rods '31 and 13 project from the rear ends of the booms 3B for connectionwith the sleeves 73 which are in alignment with the booms. I have shown yokes 01' forks on the rear ends of "the rods 31'! and '13 for straddling the sleeves with suitable pivot pins 8 l engaged through openings the yokes and sleeves. With this form of mounting the stabilizer ring '23 is carried for movement about vertical and horizontal axes.

As above described the tail surface element 23 may be incorporated in aircraft of various classes :and designs :andmay be modified in configuration to adapt it for embodiment in the particular craft. Accordingly where the terms ring, ring-Hike, annular, etc, are applied to the element 23 such terms are to be given a broad interpretation and are to be construed :as conttemplating ovate forms and other configurations that are :not truly circular.

Having described only typical forms -of the invention we do not wish to be limited to the specific details herein set forth, but wish to reserve to sourselves any variations or modifications that may appear to those skilled in the art or rfall within the scope of the following claims.

Iclaim:

1. In an airplane having a fuselage, the combination of propulsive propeller means at the aft :end of the fuselage, a substantially annular stabilizer encircling the propeller means in sufficiently :close relation thereto to increase the propulsive efiicierrcy thereof and arranged in substantially concentric relation to the longitudma-l axis of the airplane, a boom extending upwardly and rear-wamclly from the fuselage, means carried by the boom and engaged with the upper peripheral portion of the stabilizer to support the same 'for movement about a genera-l-ly vertical axis, means engaged with the forward edge of the stabilizer at opposite sides of the longitudinal :axis supporting the stabilizer for movement about a generally horizontal means liacting through the medium of the first named means :for moving the stabilizer about said horizontal axis, and means acting through the medium of the second named means for moving the stabilizer about said vertical axis, said movements of the stabilizer serving to control the direction of flight.

'2. in an airplane having a fuselage and wings, the combination of propulsive propeller means at the aft end of the fuselage, a substantially annular stabilizer encircling the propeller means in sufliciently close relation thereto to increase the propulsive efficiency thereof, booms extendm rearmrdly :from 'the wings and fuselage, means on two of said :booms directly engaging the stabilizer at opposite sides of its longitudinal axis for supporting the stabilizer for movement about a. horizontal axis, means on another of said booms directly engaging the stabilizer to provide for movement about a vertical .axis, and .a control system operable to move the stabilizer aboutsaid axes so that the stabilizer controls the direction of flight.

3. In an airplane having a fuselage and wings, the combination of propulsive means at the aft end of the vfuselage, a substantially annular stabilizer encircling the propulsive means in suf- .fic'iently close relation thereto to increase the propulsive elficiency thereof booms extending .rearwardly from the wings and fuselage, means .on two of said booms directly engaging the stabilizer at opposite sides of its horizontal axis for supporting the stabilizer for movement about a generally horizontal axis, means on another of said booms directly engaging the stabilizer to provide for movement about a generally vertical axis, and control means for operating the stabilizer to govern the direction of flight comprising a fluid pressure actuated unit for moving the stabilizer about said horizontal axis, a fluid pressure actuated unit for moving the stabilizer about said vertical axis, a fluid pressure operating system for operating said units, and a control for said system including a manually operable member movable to reflect operation of said units individually or simultaneously.

4. In an airplane, an airframe structure having a fuselage and wings extending from the fuselage,'propu1sive means at the aft extremity of the fuselage, an empennage ring surrounding the propulsive means, the ring presenting stabilizing surfaces, means for supporting the ring for angular movement about axes intersecting the central fore and aft axis of the airplane including a boom extending rearwardly from each wing, a fin rising from the fuselage and extending rearwardly toward the ring, means on the booms and fin directly connected to the ring and supporting said ring for said angular move- 7 ment, and control means in the booms and fin for imparting said angular movement to the ring to control the direction of flight of the airplane.

5. In an airplane, an airframe structure having a fuselage and wings extending therefrom, propulsive means at the aft extremity of the fuselage, an empennage ring surrounding the propulsive means, the ring presenting controlling and. stabilizing surfaces, means for supporting the ring for angular movement about generally vertical and horizontal axes including a boom extending rearwardly from each wing, a fairing rising from the fuselage and then extending rearwardly toward the ring, means on the booms and fairing directly connected to said ring and supporting the ring for said angular movement, and fluid pressure actuated means in the booms and fairing for imparting said angular movement to the ring to control the direction of flight of the aircraft.

FULVIO M. on LAVAL.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS 7 Date Number Name 123,629 Hemje Feb. 13, 1872 1,327,543 Funk Jan. 6, 1920 1,742,461 Cuddy Jan. 7, 1930 1,813,645 Townend July 7, 1931 1,824,882 Fritz Sept. 29, 1931 1,957,896 Marguglio May 8, 1934 2,128,060 Spratt Aug. 23, 1938 2,137,385 Butler Nov. 22, 1938 2,160,089 Schairer May 30, 1939 FOREIGN PATENTS Number Country Date 131,497 Great Britain Aug. 28, 1919 

